[avahi] Discovery (or better removal) takes ages

[Lennart Poettering]

On Sun, 03.06.07 19:29, Maximilian Schwerin (maximilian.schwerin at buelowssiege.de) wrote:

> Hi,

Hi!

> I've integrated AVAHI into oxine (an OSD-only frontend to xine-lib). I use it to
> discover available Apple Airport Express on the local network.
> 
> What I've noticed is that - while discovering an airport express that is there
> takes no time at all - noticing that an airport express has vanished from the
> network (e.g. been shut down) takes more than an hour.

That's the Airport's fault. As it seems it specifies very long DNS
TTLs for its entries and also doesn't send Goodbye messages for them
when it shuts down.

> I can reproduce this behaviour using the tool avahi-discover. It's obvious, that
> this behaviour is not acceptable, as a user wants to see the devices that are
> there at the moment and not devices that were there an hour ago.
> 
> Is this a bug? Is there a parameter I can set to have AVAHI poll more often for
> the devices? Or do I have to poll for them myself?

Avahi does poll for devices every now and then. However it is the
registrant's duty to specify a sensible DNS TTL for its entries. We
keep the entries around as long as the registrant tells us to do so. 

If you consider this a bug please ping the Apple guys about this. They
should lower their DNS TTLs or do a better job with sending Goodbye datagrams.

Lennart

-- 
Lennart Poettering                        Red Hat, Inc.
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